Since the 1950s, antibiotics have been widely used as growth promoters in poultry diets, providing not only nutritional support but also desirable non-nutritional benefits that significantly enhanced growth performance [1]. Despite their considerable contribution to the poultry industry's development, the misuse and overuse of antibiotics have raised serious public health concerns. Several studies have documented the presence of antibiotic residues in poultry tissues and organs, posing potential risks to human health [2]. Furthermore, the emergence of antibiotic-resistant microbial strains and the horizontal transfer of resistance genes to humans have led to increasing regulatory restrictions and outright bans on specific antibiotics in animal feed, especially within the European Union [3].It is estimated that approximately 80% of antibiotics used in poultry production are intended for growth promotion, with the remaining 20% used for prophylactic purposes [4]. However, the excessive administration of antibiotics disrupts the gut microflora, damages the protective mucosa of the intestinal lining, and suppresses immune function [5], [6]. These consequences have encouraged a global shift toward natural and safer alternatives in animal nutrition.

Recent investigations have focused on the use of natural feed additives to improve animal health, oxidative stability, and reproductive performance. Notable among these are selenium, zinc, saffron, and cannabis seed powder, which have demonstrated neurochemical and hormonal benefits without harmful environmental effects [7]–[10]. In response to food safety concerns, the European Union has prohibited the use of antibiotics as growth promoters [11], prompting researchers to explore natural alternatives such as probiotics, beneficial bacteria, yeasts, fungi, and medicinal plants to enhance immunity and growth [12].Commercial formulations incorporating these alternatives have increasingly appeared in global markets [13]. Interest in medicinal plants, in particular, has grown since the early 20th century [14], due to their multifaceted properties. Several herbs, essential oils, and plant extracts have been found to enhance gut health through their antimicrobial, antioxidant, and enzyme-stimulating properties [15].

Among these, turmeric (Curcuma longa), a member of the Zingiberaceae family, stands out for its historical and medicinal significance [16]. Traditionally used as a spice and food coloring agent, turmeric has demonstrated a broad spectrum of pharmacological effects, including antifungal [17], antioxidant [18], anti-inflammatory [19], and disease-preventive properties [20]. Its bioactive compound, curcumin, comprises three major forms: curcumin I (77%), desmethoxy curcumin (17.1%), and bisdesmethoxy curcumin (3.2%) [18], [21]. Turmeric contains various nutrients and compounds such as proteins, essential oils (including zingiberene, phellandrene, cineole), curcuminoids, vitamins, and fibers [16], [22]–[24].Botanically, turmeric is native to India, Malaysia, Indonesia, and parts of the South Pacific and is commercially cultivated in India, Vietnam, and China [25]–[27]. Numerous studies have confirmed its anti-inflammatory [28], wound-healing [29], antioxidant [30], anticancer [31]–[33], and antimicrobial effects [34]–[36]. It has also shown antiviral [37]–[39], antivenom [40], hepatoprotective, and immune-modulating activities [41], [42]. Consequently, turmeric is used in traditional medicine to treat wounds, arthritis, liver disorders, jaundice, and more [43].

Given these diverse therapeutic properties, turmeric holds promise as a natural additive in poultry nutrition, potentially enhancing performance and health while reducing reliance on synthetic antibiotics.

This trial was conducted at The Animal Production Fields of Agriculture College, University of Kirkuk, during the period from 1/11/2024 to 8/12/2024 for 38 days. The aim was to study the influence of turmeric powder (Curcuma longa) as a feed additive on mean body weight, gain weight, feed consumption, feed conversion ratio (FCR), and adherence rate in broiler chicks. Rhizomes of fresh turmeric were procured from local markets, broken with a traditional mortar and fine powder acquired directly from an electronic grinding machine (SAYONA, China). The study consisted of 165 one-day-old Ross broiler chicks. Chicks had an average body weight of 38 g and were raised in a hall that was split into semi-rectangular pens with wire mesh partitions (1.25 × 1.5 m). A layer of 3–5 cm of wood shavings were spread on pens. The chicks were randomly allotted to five treatment groups with three replicates per group and 11 chicks in each replicate (stocking density: 10 birds/m²). Feed was supplemented with turmeric powder from day 1 till the conclusion of the experiment on day 38. Treatments were: T1 (control without turmeric), T2 (1.5 g turmeric /kg feed), T3 (3 g/kg feed), T4 (6 g/kg feed) and T5 (9g/kg feed). All birds were provided 23 hours of continual light exposure per day, accompanied with 1 hour of darkness in order to habituate the animals on regular occurrence of light withdraws. Environmental parameters such as temperature, ventilation, light, feeder space, drinker space and bird density were evenly monitored in all treatments. Data were subjected to statistical analysis in a Completely Randomized Design (CRD). Means separation was conducted based on Duncan’s Multiple Range Test [44] at P ≤ 0.05. Analysis was carried out using the statistical software MINITAB (2001) based on the model: Yij=μ+Ti+eijY_{ij} = \mu + T_i + e_{ij}Yij=μ+Ti+eij where YjjY_{jj}Yjj is the observed value, μ\muμ represents the general mean, TiT_iTi is the treatment effect, and eije_{ij}eij represents the experimental error, distributed as N,0,σ2N (0, σ)N,0,σ2.

The findings of the present study indicate that dietary turmeric powder (Curcuma longa) inclusion at different levels influenced (P < 0.05) the growth performance, feed intake, feed conversion ratio (FCR), and carcass yield of broilers. Tabel 1 showed that birds in T5 treatment group (addition of 9 g/kg turmeric) had the higher body weight at 35 d old (2330.91 ± 72.4 g), and this body weight was significantly higher than control group (T1) (2118.79 ± 43.26 g) (p ≤ 0.05). This effect was apparent at earlier timepoints (10- and 24-days), but in a lesser extent. Gradual increase in body weight of birds with increasing turmeric inclusion level also confirms the growth enhancing potential of turmeric, more so at the level of 9 g/kg. These results are accordance with that of [45] who observed the broiler growth was enhanced 20% when turmeric was supplemented at 10g/kg feed on day 42 compared to control diet.

The addition of turmeric powder at varying levels to broiler diets demonstrated notable effects on growth performance, feed consumption, feed conversion ratio, and dressing percentage. The treatment with 9 g/kg (T5) of turmeric powder consistently showed superior performance in terms of body weight, weight gain, feed intake, and dressing percentage, despite a less favorable feed conversion ratio on day 35. The group supplemented with 3 g/kg (T3) exhibited the most efficient feed conversion ratio, indicating better nutrient utilization. Statistically significant differences (p ≤ 0.05) were observed among treatments, suggesting that turmeric supplementation can positively influence production parameters. Therefore, turmeric powder can be considered a beneficial natural additive in poultry nutrition, especially at moderate to higher inclusion levels such as 3–9 g/kg of feed.